1. Field of the Invention
This invention relates to a novel quinoline derivative, and, more particularly, to a novel quinoline derivative which is useful as a medicine.
2. Description of the Background
There are many quinoline derivatives known in the art. Among them, di-substituted quinoline derivatives having a pharmaceutical activity are quinophene having analgesic or antiphlogistic activities, dibucaine hydrochloride possessing anaesthetic activity, chloroquine phosphate, pentaquine phosphate and quinine used as an antimalarial agent, and quinidine as an antiarrhythmic agent. There has been, however, no knowledge surfaced about a pharmaceutical effect of 5,8-di-substituted quinoline derivatives.
The present inventors have synthesized various 5,8-di-substituted quinoline derivatives to study their pharmaceutical effects, and found that the novel compound represented by the following formula (I) exhibited a strong cardiotonic or vasodilative activity and was useful as a medicine for coronary disease treatment. Such a finding has led to the completion of this invention.